When digitally processing content (e.g., encoding or decoding), memory may be used for buffering, for example, intermediate results of a processing stage or for storing data as it is passed from one processing stage to another. Although content can be secured within a processing chip during a particular process stage, the content is still vulnerable, for example, while being written to, read from or held in a memory buffer.
FIG. 1 shows a block diagram illustrating an example of a system in which content is not secured. The system 10 may include, for example, a signal processing unit 30 coupled to an external memory storage device 40 (e.g., a hard drive). The signal processing unit 30 may be part of a set top box 20 that, for example, receives audio and visual content over multiple channels. The signal processing unit 30 is coupled to the external memory storage device 40 via a connection 70. The signal processing unit 30 is also coupled to a connection 50 and to a connection 60. Incoming content is typically encrypted when placed on the connection 50 from a central content provider (not shown) to the subscriber. The encrypted content is then decrypted, decoded or otherwise processed by the signal processing unit 30. In processing (e.g., decrypting, decoding, etc.) the incoming content, the signal processing unit 30 uses the external memory storage device 40, for example, for reading and writing content information, for buffering content information during intermediate stages of processing, etc. When the signal processing unit 30 finishes processing the incoming content, the system 10 outputs the desired output content (e.g., audio/visual content for a channel for which access has been authorized) on the connection 60 to another device (e.g., a display device).
However, once the incoming content has been decrypted by the signal processing unit 30, the content can become unsecured when stored in the external memory storage device 40 or when sent or received on the connection 70 between the signal processing unit 30 and the external memory storage device 40. Thus, unencrypted content may be accessed or copied by accessing the external memory storage device 40 or by tapping the connection 70 between the signal processing unit 20 and the external memory storage device 40. Such unsecured content may then be rebroadcasted, retransmitted or copied for delivery to an unintended or unauthorized audience.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of ordinary skill in the art through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.